From: Bart Van Assche <Bart.VanAssche@sandisk.com>
To: "linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
"nefelim4ag@gmail.com" <nefelim4ag@gmail.com>
Subject: Re: LIO: FILEIO vs IBLOCK read performance
Date: Wed, 1 Feb 2017 19:55:21 +0000 [thread overview]
Message-ID: <1485978900.2560.9.camel@sandisk.com> (raw)
In-Reply-To: <CAGqmi770AJ1v5188DijUB6oNZvsrRAMca4yeo=mqe1AW_x-Zjw@mail.gmail.com>
On Wed, 2017-02-01 at 11:18 +0300, Timofey Titovets wrote:
> so, short results (random read on /dev/sdb on client):
> block + /dev/sdb ~ 500 iops (emulate_write_cache=0)
> fileio + /dev/sdb ~ 90 iops (emulate_write_cache=0)
> fileio + /dev/sdb ~ 90 iops (emulate_write_cache=1)
> fileio + /storage/LUN/1 ~90 iops (emulate_write_cache=0)
> fileio + /storage/LUN/1 ~90 iops (emulate_write_cache=1)
> block + /dev/loop0 ~ 90 iops loop directio=0
> block + /dev/loop0 ~ 500 iops loop directio=0
The address of the LIO mailing list is target-devel@vger.kernel.org instead
of linux-scsi@vger.kernel.org. Anyway, have you tried to disable readahead
on /dev/sdb (blockdev --setra / --setfra)? Readahead can have a significant
negative impact on random I/O. There is a heuristic in the kernel for
automatically disabling readahead for random I/O but maybe that algorithm
did not recognize your workload properly.
Bart.
prev parent reply other threads:[~2017-02-01 19:55 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-01 8:18 LIO: FILEIO vs IBLOCK read performance Timofey Titovets
2017-02-01 19:55 ` Bart Van Assche [this message]
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